Many freight logistic companies attach tracking devices to aircraft containers to track their geographic location. This allows the logistic company to determine the geographic location of the container as it moves between the origination and destination points to determine whether the goods inside the container are on time, late, or might somehow be misplaced. For instance, the container may have been misrouted or been placed on the incorrect aircraft to reach its destination. The advantages of tracking the position of the goods are many and therefore have become commonplace throughout the shipping industry.
The tracking devices associated with the container transmit and receive various types of communication signals for determining the geographic position. A problem occurs when the container with the tracking device is loaded onto a transportation vessel, such as an aircraft, as the tracking signals may potentially cause interference with the aircraft systems. Regulatory agencies, such as the Federal Aviation Administration (FAA), have restrictions on communications signals due to their potential interference with flight systems and communications. Therefore it is necessary that the tracking device be deactivated while the aircraft container is on board the transportation vessel. Electronic devices may also cause undesired interference with other types of transportation vessels, in addition to aircraft, if such electronic devices are not deactivated or disabled.
Because aircraft do not include automatic detection systems that are capable of detecting when an electronic device having a field-emitting device is being used on the aircraft, the airlines rely on employees and other persons to ensure that electronic devices are not used in an improper manner. For example, passengers are requested to turn off all electronic devices that may cause interference with the aircraft systems in an unsafe manner, and flight attendants then visually inspect the passengers. This process has the goal of eliminating the possibility that a passenger may use a field-emitting electronic device while on-board the aircraft. Unfortunately, flight attendants cannot check the cargo hold, although other employees do. Still further, depending on the design of the transmitter on the cargo container, one unskilled in the area of tracking devices and systems probably cannot determine whether or not a tracking device is active or inactive. Thus, the airlines depends on the tracking device system and the personnel using it and responsible for it.
It has been determined that it is inadequate to rely on manually switching ‘off’ the tracking device when it enters the aircraft. For instance, human operators may forget to deactivate the tracking device when the container is entered into the transportation vessel. Additionally, these containers are normally tightly packed into the transportation vessel cargo hold in such a manner that they are not easily accessible once the transportation vessel has been completely loaded. One container with a tracking device still activated that is loaded onto a transportation vessel may require that the entire transportation vessel be unloaded to access and deactivate the tracking device. Further, once the container is removed from the transportation vessel at the end of its journey, the tracking device must be reactivated so the container can again be adequately tracked. To eliminate these problems, the tracking device of the present invention can automatically deactivate itself when located in the airplane cargo hold.
U.S. Pat. No. 6,281,797 describes tracking devices that use detection of frequency signals to indicate the proximity of a transportation vessel and thereafter automatically deactivate a field-emitting device and/or a tracking device associated with an electronic device and/or a shipping container. However, a problem may occur if the frequency detector fails to operate properly and detect a transportation vessel due to a malfunction or other error. If the frequency detector fails, the field-emitting device and/or the container will not deactivate its field-emitting and/or tracking device systems, thereby potentially interfering with the transportation vessel systems.